install-deps.sh: install python2-{virtualenv,devel} on SUSE if needed

install-deps.sh: install python2-{virtualenv,devel} on SUSE if needed

Recent versions of openSUSE are fully Python 3 systems, but Python 2 can still
be installed on them. When Python 2 *and* Python 3 are installed, tox will try
to run unit tests ("make check" tests) on both. But the spec-file-based
mechanism used by install-deps.sh for determining "make check" dependencies only
installs python3-virtualenv and python3-devel.

Fixes: https://tracker.ceph.com/issues/23981
Signed-off-by: Nathan Cutler <ncutler@suse.com>